Customer Pass-Thru Wires
Ford added four wires for the customer to use without having to drill holes in the firewall on the Super Duty trucks. They are attached to the wire harness under the hood by the left side hood hinge. They are Red, White, Blue, and Black. The other end of these wires is located under the dash just inside of the PCM location above the brake/clutch pedal area. They are all capped with a heat shrink material to ensure they do not inadvertently contact anything.
The wires are all 14 gauge and merely pass thru the firewall with the harness.
On my 2002 Super Duty inside the cab there are two additional wires. One is Light Blue with a Yellow trace and the other is Light Green with a White trace. The LB-YE wire is circuit 322 which is the PTO circuit. The LG-WH wire is circuit 76 which is a clean tachometer feed for aftermarket up-fitters.
